reportTitle property Null safety

Implementation

String get reportTitle {
  String title = "";

  if (type == ReportType.sensorRemoval) {
    title = "센서 ${sensor?.id} (${cow!.managementNumber})";
  } else if (type == ReportType.gatewayNeedCheck) {
    title = "게이트웨이 G104";
  } else {
    title = "${cow?.managementNumber}";
    if (cow?.name != "") {
      title = title + "(${cow?.name})";
    }
  }

  return title;
}